Carb HELP!!!

Discussion in 'General IH Tech' started by everyothertime, Jun 26, 2009.

  1. everyothertime

    everyothertime Farmall Cub

    Okies... here's the deal, attached is a bunch of pictures of a Carb, that I believe is a 4 Barrel with a restricter Plate attached to it, cause I've tried to move the lil plates under the flap to open it up but they won't budge... does this mean that Iv'e got the wrong carb on there? do I just need a two barrel? or did someone just want to be flashy and restrict the damn carb? I really would like some help on this one guys... I'm still rather an autimotive idiot...
  2. everyothertime

    everyothertime Farmall Cub

    as you can see in the big holes there's two silver lil plates, and those plates don't move at all!!! can someone tell me what I'm looking at??? and I think I need a new carb, so what am I looking at getting? or what should I get as a replacement???
  3. Blind Driver

    Blind Driver Farmall Cub

    You may have a Thermoquad on a squarebore intake :oops:

    With the restricter plate, at least you can run Talladega now :punk:
  4. robrob

    robrob Farmall Cub

    So the big boys will pop in here in a minute and give proper answers. I am too a noob but just went through the similar question. The thermo quad is 4 barrel and a spreadbore which mean most of the time the 2 small barrels open and you get better mileage.

    I also learned that the TQ is both loved and thing next to fuel injection worst thing since smog pumps....what I figured out was the can be finicky and tough to dial in....I dont really know personally.

    Locally folks round here tend toward the edelbrock carbs and I followed suit. Went with a 1406 which needs an adapter (from square bore to spread bore) and requires a little adapter for the throttle/linkage hookup (not really sure which)

    Any way hope thi I will get out of the way and let the folks who actually know what they are talking about answer. Good luck
  5. scoutboy74

    scoutboy74 Y-Block King

    That's a Thermobog which would have been OE on a late '70's SII. The intake manifold should be a spreadbore to match the carb unless some unknowing PO swapped a squarebore on there. There's no restrictor plate. I think what you're looking at is the secondary throttle plates. It wouldn't hurt anything to remove this carb for a closer inspection. Just make good note of vacuum hose routing, throttle linkage assembly and other assorted items so that you can put it all back the way it was.
  6. 1975IH200

    1975IH200 High Wheeler

    The "lil plates" are the throttle plates. They only move when you actuate the throttle pedal / linkage. Your hand is opening the choke plate (primary) and secondary air valve (secondary) which are both spring loaded closed and opened by the vacumn choke pull-off (primary) and air flow (secondary).

    The TQ used by IH is a 750-800 CFM unit.

    What exactly is the problem you believe that you have? Does your truck start & run?
    Last edited: Jun 28, 2009
  7. everyothertime

    everyothertime Farmall Cub

    Ok first a little bit about the Scout,
    its a 1979 Scout II traveler (345 engine that needs to be cleaned up a bit) I use it for both offroading and part time driver out in town. I plan to make it more of an offroading vehicle though.
    What is going on is the two silver plates in the big holes don't move at all and have never moved since I've owned it, I'm running Rich and wasting a lot of gas, also I'm pushing a lot of carbon out of my exhaust and fuell seems to be leaking from the carb. a guy at auto zone said I'm gonna have to replace my carb (but he's from autozone, and he's probably trying to sell me one).
    I looked at it with the choke propped open and revved the engine up to higher RPMs and the plates just don't move at all, I even tapped on them a little bit (with a screwdriver) to see if they would move which they don't. The only holes that are breathing at all are the little ones. I took it to a Mechanic and he said it might have seized or it might just need to be taken apart and cleaned up. However, it still starts up and runs with the two little holes working fine, and only recently have I been having problems. Thats where I'm getting confused. the mech told me that it was a very good Carburetor when it was new, now its a really bad one! :censored:
  8. Doc Stewart

    Doc Stewart Content Team Staff Member Moderator

    The Thermoquads with the plastic bodies generally are junk although someone on here has fixed one. If that's what you have, get an Edelbrock! If you have the all-metal TQ, get a kit and rebuild it then tune it to match your engine.
  9. Afireinside2285

    Afireinside2285 High Wheeler

    Do search for themoquad and you will get more info. than you want.
    The secondary barrels(big ones) don't open all the time.It's easy to check if you know what your doing.
    That should be factory carb for 79 345
    Good luck
  10. Mike_Ert

    Mike_Ert Farmall Cub

    The secondaries won't open until your foot is really into it. On the Thermoquad they are controlled through manual linkages. While looking down on the carb open both choke plates then actuate the throttle to full throttle manually. If you don't see both the primary and the secondary plates open you have a problem.
  11. IHWILD

    IHWILD High Wheeler

    I was pretty sure that the secondaries are vacuum operated but also have sort of an interlock with the linkages. Ie they have to be at a certain throttle position before the vacuum can pull them open. There is even an adjustment on the side which you adjust the vacuum point that they come in at.
  12. Mike_Ert

    Mike_Ert Farmall Cub

    I may be wrong but I thought the air door/choke plate on the top is vacuum operated, the actual throttle plates are via linkages.
  13. Afireinside2285

    Afireinside2285 High Wheeler

    The secondaries are basicly vacume operated with mech linkage.
  14. Mike_Ert

    Mike_Ert Farmall Cub

    LOL, well what the hell do I know anyhow. I had to many problems with my Thermoquad and swapped on a Quadrajet. :hammer:
  15. IHWILD

    IHWILD High Wheeler

    I'm probably skipping the quadrajet and going right to FI lol

    If the poster needs help I'd suggest getting a service manual or I can try to look it up and explain anything he needs though I might need correction or translation lol... As long as it is Stock for his scout it shouldn't be too far off.

  16. Afireinside2285

    Afireinside2285 High Wheeler

    It sounds to me like the fuel bowl is leaking on the bottom two plugs.
    good luck
  17. everyothertime

    everyothertime Farmall Cub

    I just put in an order for a Owners manual/tech book.
    Last edited: Jun 27, 2009
  18. everyothertime

    everyothertime Farmall Cub

    I've got the plastic I think I'll just get a new carb. any Ideas???
  19. Erik VanRenselaar

    Erik VanRenselaar Y-Block King

    What manual did you order?

    The carburetor you have is NOT a Quadrajet; one of your photos plainly shows that it is a Carter ThermoQuad carburetor. I am not aware of a *bad* version of a ThermoQuad, but I do know that my friend (Rusty Scout, here on BP) and I rebuilt the stock T-Quad on his '79 Scout II over 15 years ago, and it still works quite well.
    If a T-Quad is properly built, it can be a very good performer, that's economical, too.
  20. Erik VanRenselaar

    Erik VanRenselaar Y-Block King

    I have never heard of, or seen (photo or in-person) a Carter ThermoQuad carburetor with an all-metal body. The phenolic plastic lower body is what makes the *Thermo* in the carb's name. It insulates the fuel in the float bowls from the heat of the engine.

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